Department of Aerospace Engineering

Distinguished Lecture Series in Aerospace Engineering; Alejandro Diaz, MSU; "Modal Disparity and its Application in Control of Flexible Structures"

Alejandro Diaz, MSU

This seminar will be held at 2:10 PM in the Alliant Energy-Lee Liu Auditorium, 1140 Howe Hall.

MODAL DISPARITY AND ITS APPLICATION IN CONTROL OF FLEXIBLE STRUCTURES

Modal control remains the standard strategy for control of flexible structures. It relies on assumptions of linearity and controllability and observability of all significant modes of the system and typically requires a large number of sensors and actuators and a high-dimensional state-space model. For large space structures, this increases cost from both hardware and payload considerations and results in increased control complexity arising from modal truncation. In this presentation  a new methodology is introduced  that enables simple control designs for flexible structures, a methodology that provides control authority over all significant flexible modes using only a small number of sensors and actuators and a low-dimensional state space model. The methodology relies on a carefully crafted variation in the stiffness of the structure to achieve modal energy redistribution, and supports the use of a relatively simple control design to dissipate energy from only a few specific modes. This allows, in principle, vibration suppression through control of a few selected modes. The success of the strategy relies on the ability to generate significant stiffness variation in a given structure, resulting in what we define as modal disparity. Maximization of modal disparity is formally posed as an optimization problem, which addresses the optimal design of the system used to introduce stiffness variations in a given structure.  The work presents a topology optimization problem seeking to maximize modal disparity  using various methods to introduce stiffness variation, including cables, careful positioning of non-structural masses, and variable stiffness joints.  

 
A reception will be held following this seminar.